Valid being you could connect to the bank who issued their card or valid being you are looking for certain characteristics of the number to give it a "better" chance of being a real and valid card number?
Well, determining if the number is valid is using the Luhn formula -- it's just a credit card check. 414 will beat it. Is that what you're asking? It doesn't tell you if the user has any money left on it.<BR><BR>If so, you'll have to code for it.
>>Is it possible to charge their Credit Card on online?<BR><BR>Of course!! There are thousands of sites that do it.<BR><BR>You have to set some things up though... try these sites for tutorials and services:<BR><BR>http://www.verisign.com<BR>http://www.paypal.com